Organic composite-plated steel plate and resin composition for coating material used therein

ABSTRACT

The present invention comprises an improved organic composite-plated steel plate which is obtained by applying a thermosetting resin to a chromate-coated alloy-plated steel plate and curing this, wherein, various aqueous resin compositions having the form of basic coating film formation components, such as, for example, aqueous vinyl modified epoxy ester resins, or aqueous vinyl modified epoxy ester resin / blocked isocyanate compound-types, or aqueous vinyl modified epoxy ester resin / blocked isocyanate compounds / colloidal silica-types, are used as the thermosetting resin described above. In accordance with the present invention, it is possible to provide an organic composite-plated steel plate which is novel and has extremely high applicability in a form in which an aqueous resin (composition) for organic composite coating, which has superior adhesion with adhesives, superior continuous welding properties, superior post-working corrosion resistance, and superior electro-deposition coating properties, and moreover, has superior coating material adhesion and corrosion resistance, and the coated surface of which, after electro-deposition coating, has particularly superior shininess (smoothness), and which furthermore has superior rust resistance and does not use large amounts of organic solvent, is pre-coated onto a metallic material.

This is a division of application Ser. No. 08/360,735 filed Mar. 1, 1995now U.S. Pat. 5,637,403, which is a U.S. national stage applicationunder 35 USC 317 of application PCT/JP94/00674 filed Apr. 22, 1994.

FIELD OF THE INVENTION

The present invention relates to an organic composite-plated steel platewhich is novel and useful, as well as to a resin composition for coatingmaterial which is used in the coating thereof. In greater detail, thepresent invention relates to an organic composite-plated steel plate,which is obtained by applying a specified organic resin or a compositioncontaining a specified organic resin to a specified chromate-coatedplated steel plate and curing this, which has in particular superioradhesion with adhesives, superior continuous welding properties,superior post-working corrosion resistance, superior electro-depositioncoating properties, superior high corrosion resistance, and superiorcoating material adhesion, as well as to a resin composition for coatingmaterials.

In addition, it has been discovered that the mixture on the molecularlevel with the specified organic resin of a blocked isocyanate compoundas a curing agent provides an organic composite-plated steel plate whichhas particularly superior rust resistance; the present inventionprovides an organic composite-plated steel plate having such a specifiedform.

BACKGROUND ART

As a result of problems associated with organic solvents constituting incoating materials, such as the combustibility thereof, atmosphericpollution, worker safety, and sanitation problems, it has been hoped arapid shift from organic-solvent-based coating materials to water-basedcoating materials.

On the other hand, in the field of automobiles, steel household items,and household electrical appliances, the use of pre-coated metalmaterials has been increasing in order to improve productively.

Accordingly, in the field of surface preparation and coating, as well,in order to respond to such demands, various coating materialcompositions for use in pre-coated metal materials have been developed;however, in this field, as well, the shift from conventionalorganic-solvent-based coating materials to water-based coating materialsis strongly desired.

Furthermore, in systems employing conventional organic-solvent-basedcoating materials, in order to obtain the conductively which is anecessary condition for conducting an electro-deposition coating, theinvention disclosed in, for example, Japanese Patent Application, SecondPublication, No. Sho 45-2430 and Japanese Patent Application, SecondPublication, No. Hei 4-6882, disclose zinc-rich coating materials. Suchzinc-rich coating materials are capable of electro-deposition coating;however, the smoothness of the coated surface is insufficient.Furthermore, in such zinc-rich coating materials, the coating film isunstable with respect to rust produced in the case in which corrosionoccurs, and it is impossible to guarantee corrosion resistance over along period of time (resistance to rust cannot be guaranteed), andmoreover, after working, the coating film is easily fractured, and thusthe resistance to corrosion after working is poor.

On the other hand, the inventions disclosed in Japanese PatentApplication, Second Publication, No. Sho 52-44569, Japanese PatentApplication, Second Publication, No. Sho 58-19706, and Japanese PatentApplication, First Publication, Laid-Open No. Sho 51-79138 and JapanesePatent Application, First Publication, Laid Open No. Sho 58-138758provide coating materials having a form into which conductive pigment isblended in order to make electro-deposition coating possible.

However, in such coating materials, particulate pigment possessing arelatively large particle diameter, wherein the average particlediameter is 1 micron (μm) or more, such as metallic powders of zinc,metallic carbide powders, or metallic phosphate powders, are employed asthe conductive pigment. For this reason, unevenness is produced on thecoating film which is formed, or, during press working, flaws resultingfrom the conductive materials which are added are deposited on thesurface of the steel plate, and such unevenness or flaws remain on thesurface of the electro-deposited coating, and as a result, even aftertwo or three coats, there is a problem in that such unevenness or flawsremain on the coating film surface, and there is a disadvantage in that,as a result thereof, it is also impossible to guarantee rust resistance.

Furthermore, in Japanese Patent Application, First Publication, LaidOpen No. Sho 58-224174, Japanese Patent Application, First Publication,Laid Open No. Sho 60-197778, Japanese Patent Application, FirstPublication, Laid Open No. Sho 60-199074, and Japanese PatentApplication, First Publication, Laid Open No. Sho 60-174879, inventionsrelating to organic composite silicate coating films and steel platescoated with such coating films are disclosed. These organic silicatecoating films do not contain conductive pigments and are extremely thincoating films having a thickness within a range of 0.2˜5.0 microns (μm), and possess high corrosion resistance as a result of bonds between anorganic binder and colloidal silica, so that such coating filmsrepresent a noticeable improvement, particularly in press workability.

However, the problem of unevenness in the electro-deposited coating filmis present, and in particular, there is a problem in that the coatingfilm thickness of the electro-deposited coating film formed on theorganic composite silicate coating film varies greatly in correspondencewith the variation in the thickness of the organic composite silicatecoating film. That is to say, in places in which the organic compositesilicate coating film is thick, the electro-deposited coating filmbecomes thick, while in place where the coating film is thin, theelectro-deposited coating film becomes thin. Accordingly, there is aproblem in that as a result of the electro-deposited coating film, thoseunevennesses are magnified. Additionally, all of these organic compositesilicate coating films exhibit a tendency to have poor rust resistance.

Furthermore, the problems described above were solved to a considerableextent by means of methods disclosed in Japanese Patent Application,First Publication, Laid Open No. Sho 62-2833161, and Japanese PatentApplication, First Publication, Laid Open No. Hei 3-269067; however,these methods possess problems. That is to say, in these methods, theuse of a special organic solvent, or the use of special additives, wasnecessary, and there was a problem in that the adhesion thereof withadhesives such as vinyl chloride sol or the like is poor, and inaddition, the electro-deposited coating film lacks a sense ofglossiness, that is to say, the coating film is not shiny, and thesmoothness thereof is insufficient. In addition, since it is necessaryto apply an extremely thin coating film, it is necessary to sufficientlydilute the coating material which is used, and in order to do this, itis necessary to employ a large amount of organic solvent.

In view of the problems and defects present in the conventionaltechnology, the present inventors began research in order to obtain anorganic composite-plated steel plate which did not have the problemsdescribed above and was novel and possessed great usefulness.

That is to say, the present invention has as an object thereof toprovide an organic composite-plated steel plate which is novel andpossesses great usefulness, is in a form in which an aqueous resin fororganic composite coating which, in particular, has superior adhesionwith adhesives, has superior continuous weldabilities, has superiorresistance to corrosion after working, and superior electro-depositioncoating, and moreover, has superior coating material adhesion andresistance to corrosion, and in particular, the coated surface of whichhas superior shininess (smoothness) after electro-deposition coating,and furthermore, which has superior rust resistance and the like, andwhich additionally does not employ large amounts of organic solvent, ispre-coated on a steal material.

DISCLOSURE OF THE INVENTION

The improved organic composite-plated steel plate in accordance with thepresent invention is an organic composite-plated steel plate obtained byapplying a thermosetting resin to a chromate-coated alloy plated steelplate and curing the thermosetting resin, wherein as the thermosettingresin described above, an aqueous resin composition is employed whichcontains, as a necessary coating film formation component, an aqueousvinyl modified epoxy ester resin obtained by modifying an epoxy esterresin, obtained by the reaction of an aromatic epoxy resin and a fattyacid, by means of the addition reaction of a vinyl monomer having anethylenic vinyl monomer containing a carboxylic group as a necessarycomponent, and neutralizing the modified epoxy ester resin using a basiccompound.

Furthermore, the improved organic composite-plated steel plate inaccordance with the present invention is an organic composite-platedsteel plate which is obtained by applying a thermosetting resin to achromate-coated alloy plated steel plate and curing the thermosettingresin, wherein as the thermosetting resin described above, an aqueousresin composition is employed which comprises a curing agent and anaqueous vinyl modified epoxy ester resin which is obtained by modifyingan epoxy ester resin, which is obtained by the reaction of an aromaticepoxy resin and a fatty acid, by means of the addition reaction of avinyl monomer having as a necessary component thereof an ethylenic vinylmonomer containing a carboxylic group, and a neutralization of themodified epoxy ester resin using a basic compound.

Furthermore, the improved organic composite-plated steel plate inaccordance with the present invention is an organic composite-platedsteel plate which is obtained by applying a thermosetting resin to achromate-coated alloy plated steel plate and curing the thermosettingresin, wherein as the thermosetting resin described above, an aqueousresin composition is employed which comprises an aqueous vinyl modifiedepoxy ester resin obtained by modifying an epoxy ester resin, obtainedby a reaction of an aromatic epoxy resin and a fatty acid, by means ofan addition reaction of a vinyl monomer having as a necessary componentthereof an ethylenic vinyl monomer containing a carboxylic group, andthe neutralization of the modified epoxy ester using a basic compound,and at least one selected from the group consisting of a powder and acolloid (sol) comprising at least one of SiO₂, Cr₂ O₃, Fe₂ O₃, Fe₃ O₄,MgO, ZrO₂, SnO₂, Al₂ O₃, and Sb₂ O₅.

Furthermore, the improved organic composite-plated steel plate inaccordance with the present invention is an organic composite-platedsteel plate which is obtained by applying a thermosetting resin to achromate-coated alloy-plated steel plate and curing the thermosettingresin, wherein as the thermosetting resin described above, an aqueousresin composition is employed which comprises an aqueous vinyl modifiedepoxy ester resin obtained by modifying an epoxy ester resin, obtainedby a reaction of an aromatic epoxy resin and a fatty acid, by means ofan addition reaction of a vinyl monomer having as a necessary componentthereof an ethylenic vinyl monomer containing a carboxylic group, and aneutralization of the modified epoxy ester resin using a basic compound,a curing agent for the aqueous vinyl modified epoxy ester resin, and atleast one selected from the group consisting of a powder and a colloid(sol) comprising at least one of SiO₂, Cr₂ O₃, Fe₂ O₃, Fe₃ O₄, MgO,ZrO₂, SnO₂, Al₂ O₃, and Sb₂ O₅.

The improved organic composite-plated steel plate in accordance with oneof claims 1 through 4 has, in particular, superior adhesion with anadhesive, superior continuous weldabilities, superior resistance tocorrosive properties after working and superior electro-depositioncoating properties, and moreover, has superior coating material adhesionand resistance to corrosion, and in particular, has superior shininess(smoothness) of the coated surface after electro-deposition coating.

Furthermore, when an aqueous resin composition in which a blockedisocyanate compound and vinyl modified epoxy ester resin are mixedhomogeneously on the molecular level is used in place of the aqueousvinyl modified epoxy ester resin and curing agent therefor, then thereis an advantage in that an organic composite-plated steel plate isobtained which has particularly superior rust-resistance.

BEST MODE FOR THE EXECUTION OF THE INVENTION

As described above, the present invention have conducted diligentresearch in order to solve the problems described above, and as aresult, have arrived at the present invention.

That is to say, fundamentally, the present invention provides,respectively:

(1) an improved organic composite chromate coated alloy-plated steelplate formed by using an aqueous resin composition containing, as anecessary coating film formation component, and aqueous vinyl modifiedepoxy ester resin, which is obtained by modifying an epoxy ester resin,obtained by the reaction of an aromatic epoxy resin and a fatty acid, bymeans of the addition reaction of a vinyl monomer having as a necessarycomponent thereof an ethylenic vinyl monomer containing a carboxylicgroup, and neutralizing the modified epoxy ester resin using a basiccompound;

(2) an improved organic composite chromate coated alloy plated steelplate formed by using an aqueous resin composition comprising a curingagent and an aqueous vinyl modified epoxy ester resin obtained bymodifying an epoxy ester resin, obtained by the reaction of an aromaticepoxy resin and a fatty acid, by means of the addition reaction of avinyl monomer having as a necessary component thereof an ethylenic vinylmonomer containing a carboxylic group, and neutralizing the modifiedepoxy ester resin using a basic compound;

(3) an improved organic composite chromate-coated alloy-plated steelplate formed by using an aqueous resin composition comprising an aqueousvinyl modified epoxy ester resin obtained by modifying an epoxy esterresin, obtained by a reaction of an aromatic epoxy resin and a fattyacid, by means of an addition reaction of a vinyl monomer having as anessential component thereof an ethylenic vinyl monomer containing acarboxylic group, and a neutralization of the modified epoxy ester resinusing a basic compound, and at least one selected from the groupconsisting of a powder and colloid (sol) comprising at least one ofSiO₂, Cr₂ O₃, Fe₂ O₃, Fe₃ O₄, MgO, ZrO₂, SnO₂, Al₂ O₃, and Sb₂ O₅ ; and

(4) an improved organic composite chromate-coated alloy-plated steelplate formed by using an aqueous resin composition comprising an aqueousvinyl modified epoxy ester resin obtained by modifying an epoxy esterresin, obtained by a reaction of an aromatic epoxy resin and a fattyacid, by means of an addition reaction of a vinyl monomer having as anessential component thereof an ethylenic vinyl monomer containing acarboxylic group, and a neutralization of the modified epoxy ester resinusing a basic compound, a curing agent for the aqueous vinyl modifiedepoxy ester resin, and at least one selected from the group consistingof a powder and a colloid (sol) comprising at least one of SiO₂, Cr₂ O₃,Fe₂ O₃, Fe₃ O₄, MgO, ZrO₂, SnO₂, Al₂ O₃, and Sb₂ O₅ ; and

furthermore, the present invention provides:

a resin composition for coating material for chromate-coatedalloy-plated steel plates, comprising

an aqueous vinyl modified epoxy ester resin (A-1), obtained by themodifying of an epoxy ester resin, obtained by a reaction of an aromaticepoxy resin and a fatty acid, by means of an addition reaction of avinyl monomer having as a necessary component thereof an ethylenic vinylmonomer possessing a carboxylic group, and a neutralization of themodified epoxy ester resin using a basic compound,

at least one selected from the group consisting of a powder and acolloid (sol) (B) comprising at least one of SiO₂, Cr₂ O₃, Fe₂ O₃, Fe₃O₄, MgO, ZrO₂, SnO₂, Al₂ O₃, and Sb₂ O₅,

a curing agent (C), and

if necessary, a pigment composition (D); and furthermore,

a resin composition for coating materials for chromate-coatedalloy-plated steel plates comprising

an aqueous vinyl modified epoxy ester resin (A-2) containing a blockedisocyanate compound obtained by mixing homogeneously on the molecularlevel so as to be aqueous, a blocked isocyanate compound and a vinylmodified epoxy ester resin, in which an epoxy ester resin, obtained bythe reaction of an aromatic epoxy resin a fatty acid, is modified, bymeans of the addition reaction of a vinyl monomer having as a necessarycomponent an ethylene vinyl monomer containing a carboxylic group.

at least one selected from the group consisting of a powder and acolloid (sol) (B) comprising at least one of SiO₂, Cr₂ O₃, Fe₂ O₃, Fe₃O₄, MgO, ZrO₂, SnO₂, Al₂ O₃, and Sb₂ O₅,

if necessary, a curing agent (C), and

if necessary, a pigment (D).

(5) In addition, the present invention provides an improved organiccomposite chromate-coated alloy-plated steel plate employing,concretely, a specified resin composition in a form in which the aqueousvinyl modified epoxy ester resin and curing agent therefor are obtainedby homogeneously mixing, on the molecular level, a vinyl modified epoxyester resin and a blocked isocyanate compound, so as to be aqueous.

The present invention also provides an organic composite-plated steelplate which is obtained by applying the various aqueous resincompositions in (1)-(5) above, and curing these; the organic coatingfilm thickness thereof is within a range of 0.2-3.0 g/m².

What is meant by the "chromate-coated alloy-plated steel plate" in thepresent invention is a plated steel plate which is further coated with achromate coating film on a surface thereof, wherein the plated steelplate is plated with either various single elements (metallic singlesubstance) such as Zn, Ni, Cu, Sn, Co, or Al, or various alloys, forexample, Zn--Ni alloy, Zn--Fe alloy, Zn--Cr, Zn--Cu alloy, Zn--Mn alloy,Zn--Al alloy, Zn--Mg alloy, or in Zn--Cr--Nifl alloy.

Among these, Zn or Sn, or a Zn alloy, are appropriate for use as theplating substance, and more preferably. Zn or a Zn alloy areappropriate.

Here, what is meant by a "chromate coating film" is a chromiumpassivated coating film comprising a composite having trivalent andhexavalent chromium hydroxides as main components, in a form obtained bycoating electrolytic-type chromate, applied-type chromate, orreactive-type chromate, and drying and curing this.

Furthermore, herein, an amount of deposited chromium of the chromatecoating film within a range of 10 to 150 mg/m² is appropriate. When theamount of deposited chromium is less than 10 mg/m², it tends to becomeimpossible to form an organic coating film having superior adhesion, andmoreover, there is a tendency for corrosion resistance to decline aswell, while on the other hand, at excessive levels of more than 150mg/m², cohesion breakdowns of the chromate coating film occur, so thatin particular, there is a tendency for the adhesion of the coatingmaterial or the like to decline.

The present invention can be executed by applying and curing an aqueousresin composition containing, as a necessary coating film formationcomponent, an aqueous vinyl modified epoxy ester resin having aspecified composition, which is explained hereinbelow, on this type ofchromate-coated alloy-plated steel plate.

What is meant by such an "aqueous vinyl modified epoxy ester resin" is,for example, a resin which is obtained by means of the proceduresdescribed hereinbelow.

That is to say, first, an aromatic epoxy resin and a fatty acid aresubjected to an esterification reaction for a period within a range ofapproximately 2 hours to approximately 10 hours at a temperature withina range of approximately 150 to 250° C., while being heated andagitated, and this is then dissolved using a desired organic solvent. Apolymerization initiator and vinyl monomers having as a necessarycomponent thereof an ethylenic vinyl monomer containing a carboxylicgroup are added, this is heated and agitated, and a graft reaction isconducted at a temperature within a range of from approximately 50° C.to approximately 150° C., and a vinyl modified epoxy ester resin isobtained.

Next, the carboxylic group of the vinyl modified epoxy ester resinobtained in this manner is neutralized using a basic compound, and afterthis, this is dispersed in water, and thus the aqueous vinyl modifiedepoxy ester resin is obtained.

Particularly representation examples of the aromatic epoxy resin whichis used here include, for example, bisphenol A-type epoxy resin,bisphenol F-type epoxy resin, or novolak-type epoxy resin, or the like.

It is necessary that the number-average molecular weight of sucharomatic epoxy resins be within a range of approximately 800 to 6000.When the number-average molecular weight is less than 800, the corrosionresistance is poor, while when the number of the molecular weight ismore than 6000, the resin tends to be highly viscous when synthesized,and such a resin is thus difficult to use.

Particularly representative examples of commercially available aromaticepoxy resins include, for example, the "EPICOAT 152, 154, 1001, 1002,1004, 1007, 1099, and 1010" (trade names) of Shell Co., in Royal Dutch,and the "EPICLON 1050, 1055, 4050, 3050, 7050, and 9055" (trade names)of Dainippon Ink and Chemicals, Inc., and the like; it is of coursepossible to be used singly or in a combination of the two or more.

In the present invention, the aromatic epoxy resin is employed as anecessary component particularly in order to maintain corrosionresistance an in order to maintain the adhesion to the substrate, theelectro-deposited coating film, or the adhesive such as vinyl chloridesol.

The amount of this aromatic epoxy resin which is employed preferably bewithin a range of approximately 5 to 80 weight percent. When the amountthereof used is less than 5 weight percent, the effects described aboveare small, while when the amount used is in excess of 80 weight percent,the resin design becomes difficult. An amount within a range of,approximately, 10 to 60 weight percent is more preferable from the pointof view of continuous weldabilities.

Next, the use of a drying oil fatty acid as the fatty acid describedabove is desirable in order to guarantee the grafting point during thefollowing so-called "vinyl modifying". When a non-drying oil fatty acidis employed, it is necessary to guarantee the grafting point by means ofadding a small amount of one of the various unsaturated dicarboxylicacids or the like, such as maleic acid, fumaric acid, or itaconic acid.

Particularly representative examples of fatty acids which can beemployed include, for example, linseed oil fatty acid, soybean oil fattyacid, safflower oil fatty acid, repeseed oil fatty acid, sesame seed oilfatty acid, coconut oil fatty acid, palm oil fatty acid, palm kernel oilfatty acid, rice oil fatty acid, castor oil fatty acid, dehydratedcastor oil fatty acid, and the like. The amount of fatty acid employedshould be such that the sum of the fatty acid and the aromatic epoxyresin described above reach 100 weight percent.

During the esterification reaction, it is possible to use, as thereaction catalyst, various basic substances such as one of the variousimidazole derivatives such as 2-methylimidazole, or the like; one of thevarious tertiary amines such as triethyl amine or dimethylbenzyl amine;or one of the various quaternary amines such as tetramethyl ammoniumchloride. Furthermore, in order to remove the water generated by thecondensation, this esterification reaction my be conducted underrefluxing condition with toluene or xylene or the like.

Particularly representative examples of the organic solvent which isused during the vinyl modifying include, for example, varioushydrophobic organic solvents such as toluene, xylene, or mineralspirits; various alcohol-type solvents such as methanol, ethanol, orbutanol; various ether-type solvents such as methyl ether, ethyl ether,or tetrahydrofuran; various ketone-type solvents such as acetone, methylethyl ketone, methyl isobutyl ketone, or cyclohexanone; various ethyleneglycol-type solvents such as ethyl cellosolve, butyl cellosolve, orcellosolve acetate; various propylene glycol-type solvents such aspropylene glycol monobutyl ether; various diethylene glycol-typesolvents such as butyl carbitol, and the like; furthermore, it it alsopossible to use commonly-known hydrophilic organic solvents, such asN-methyl-2-pyrolidone, dimethyl formamide, dimethyl acetoamide, ordimethyl sulfoxide or the like, in freely selected proportions.

Hydrophobic organic solvents have poor dispersion stability with respectto water (aqueous dispersion stability), so that it is desirable toemploy a hydrophilic organic solvent, and furthermore, the amount usedis not particularly restricted; however, the amount employed isgenerally such that the resin solid component is within a range ofapproximately 5 to 80 weight percent.

Particularly representative examples of the polymerization initiatordescribed above which is employed during vinyl modifying include, forexample, various inorganic peroxide compounds such as potassiumpersulfate, ammonium persulfate, hydrogen peroxide, or percarbonantsalt, or the like; or various organic peroxides such as various ketoneperoxides such as methyl ethyl ketone peroxide or the like; variousperoxyketols such as 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexanone, and the like, various hydroperoxides such astert-butylhydroperoxide, and the like; various diacyl peroxides such asbenzoyl peroxide; various dialkyl peroxides such as di-tert-butylperoxide, and the like; various peroxydicarbonates such as dioxypropylperoxydicarbonate, and the like; and various peroxy esters such astert-butyl peroxy-2-ethyl hexanoate; or, various azo-type compounds suchas azobisisobutylonitrile.

Furthermore, with respect to the vinyl monomer employed, an ethylenicvinyl monomer containing a carboxyl group must be used as a necessarycomponent for the purpose of making this aqueous form, which isaccomplished in the following process. Furthermore, in the case in whicha curing agent is concomitantly used, in order to ensure sufficientcurability, the use of an ethylenic vinyl monomer containing a hydroxylgroup is also preferable.

Particularly representative examples of the ethylenic vinyl monomercontaining a carboxylic group include, for example, various unsaturatedmono- or di-carboxylic acids such as acrylic acid, methacrylic acid,crotonic acid, itaconic acid, fumaric acid, maleic acid, or citraconicacid, or the like.

Furthermore, particularly representative examples of the ethylenic vinylmonomer containing a hydroxyl group include, for example, 2-hydroxyethyl methacrylate, 2-hydroxy ethyl acrylate, 2-hydroxy propylmethacrylate, 2-hydroxy propyl acrylate, or the like. It is of coursethe case that these may be used alone, or tow or more thereof may beused concomitantly.

In addition, to these ethylenic vinyl monomers containing carboxylgroups and ethylenic vinyl monomers containing hydroxyl groups, ifnecessary, it is possible to use another ethylenic vinyl monomer whichis polymerizable with ethylenic vinyl monomers containing thesefunctional groups.

Particularly representative ethylenic vinyl monomers which may beemployed include, for example, various (meth)acrylate alkyl esters sucha (meth)acrylate methyl, (meth)acrylate ethyl, (meth)acrylate n-butyl,or (meth)acrylate lauryl; various α- or β- unsaturated amides, such asacryl amide, methacryl amide, or N-methylolacrylamide, various α- or β-unsaturated nitriles such as acrylonitrile or methacrylonitrile; variousstyrene derivatives such as styrene, α-methylstyrene or vinyl toluene;or various vinyl esters such as vinyl acetate, vinyl propionate, or"Veoba" (trade name; a vinyl ester of a branched aliphaticmonocarboxylic acid produced by Shell Co., in Royal Dutch); furthermore,various halogenated vinyls such as vinyl chloride, vinylidene chloride,or other fluorine-containing monomers; or various conjugated dienes suchas butadiene.

It is of course the case that these monomers may be used singly, or twoor more thereof may be used concomitantly. It is also the case thatother polymerizable polyester resins or alkyd resins may be usedconcomitantly.

With respect to the amount of use of the ethylenic vinyl monomersdescribed above, an amount within a range of approximately 3 to 50 partsper weight with respect to 100 parts per weight of the reaction productof the aromatic epoxy resin and fatty acid described above isappropriate, and a reaction may be carried out using these proportions.

Here, with respect to the amount of use of the ethylenic vinyl monomercontaining a carboxylic group which is the necessary component describedabove, an amount within a range of, approximately, 3 to 30 parts isappropriate. In the case when the amount used is less than approximately3 parts, the particle diameter of the aqueous dispersion which isfinally obtained tends to become large, and as a result, thesedimentation stability becomes poor, and application becomes difficult,while on the other hand, when the amount used is in excess ofapproximately 30 parts, after this is entirely neutralized using a basiccompound, it does not become an aqueous dispersion, but rather becomescompletely water soluble. In this case, when the degree ofneutralization is reduced, and aqueous dispersion is obtainable;however, there is a tendency in all cases for this to dissolve inalkaline substances, so that an organic coating film which is deficientparticularly in alkaline resistance is obtained.

Particularly representative examples of the basic compound describedabove which is employed in order to neutralize the carboxylic grouppresent in the resin when the reaction product is made aqueous in anaqueous medium include, for example, ammonia, volatile amines or thelike, and the use of such volatile substances is preferable.

In addition, inorganic basic compounds except for ammonia exhibit atendency to remain in a coating film, and to reduce, in particular, thewater resistance thereof, so that the use thereof is not preferable.

Particularly representative examples of such volatile amines include,for example, at least one selected from a group consisting of variousamines comprising monoethyl amine, dimethyl amine, trimethyl amine,monoethyl amine, diethyl amine, triethyl amine, monopropyl amine,dimethyl propyl amine, monoethanol amine, diethanol amine, triethanolamine, N-methyl ethanol amine, N-aminoethyl ethanol amine, N-methyldiethanol amine, monoisopropanol amine, diisopropanol amine,triisopropanol amine, and N,N-dimethyl propanol amine, and the like.

It may be conducted to make aqueous by neutralizing a portion or all ofthe carboxylic groups present in the reaction products using the basicsubstance, and then, dispersing the reaction products in water.

With regard to the method of dispersing the neutralized product of thereaction products in water, while agitating the neutralized product,water may be added gradually thereinto and this subjected to aphase-inversion emulsification, or the reaction products may be addedinto a sufficiently agitated water.

A method may also be adopted in which dispersion in water is conductedwhile applying mechanical shearing force by means of a homogenizer,colloid mill, static mixer, or mantongori. Furthermore, while dispersionin water is conducting, a method in which ultrasonic is applied is alsopreferable.

In this manner, it is possible to prepare the aqueous vinyl modifiedepoxy ester resin which is a necessary component in the aqueous resincomposition employed in the present invention.

With respect to the aqueous resin composition employed in the presentinvention, it is possible to concomitantly use a composition whichcontains, in addition to the aqueous vinyl modified epoxy ester resin,if necessary, a curing agent which is used in order to cure the aqueousvinyl modified epoxy ester resin, and/or a powder or a colloid (sol) ofa specified metal oxide which serves to improve the corrosionresistance.

Among these, the use of a curing agent is particularly effective inimproving the resistance to solvents and the alkaline resistance.

Particularly representative examples of curing agents to be employedinclude, for example, amino resins, blocked isocyanate compounds, dryeragents, epoxy compounds, or aziridine compounds or the like. Noparticular restriction is made with respect to the type thereof, butamong the above, the use of amino resins, blocked isocyanate compounds,or dryer agents, which possess superior storage stability in an aqueousmedium with the vinyl modified epoxy ester resin described above, isusual.

Particularly representative examples of amino resins include, forexample, various butyl etherified melamine resins, such as "SUPERBECKAMIN J-820-60, G-821-60, or L-128-60" (trade names; produced byDainippon Ink and Chemicals, Inc.); or various butyl etherified urearesins, such as "BECKAMIN G-1850 or G-196-60" (trade names; produced byDainippon Ink and Chemicals, Inc.), and like; and furthermore, variousmethyl etherified melamine resins, such as "CYMEL 300, 303, or 325"(trade names; produced by Mitsui SciTech), and the like; suchcommercially available products may be employed.

Particularly representative examples of blocked isocyanate compoundsinclude, for example, both aqueous blocked isocyanate compounds andnon-aqueous blocked isocyanate compounds; however, when non-aqueousblocked isocyanate compounds are employed, if the blocked isocyanatecompounds are added to the coating material immediately prior to use andstrongly agitated, then the stability thereof worsens, and there arecases in which sedimentation occurs, so that with respect to this point,the use of aqueous blocked isocyanate compounds is desirable.

Particularly representative examples of blocked isocyanate compoundswhich may be employed include, for example, as the blocking agent of theisocyanate group, for example, various alcohols such as methanol,ethanol, n-propanol, iso-propanol, n-butanol, iso-butanol, and the like;various phenols such as phenol, cresol, nitrophenol, chlorophenol,resorcinol, or the like; various thiokols such as benzen thiol, and thelike; various caprolactums such as ε-caprolactum; various carbamatessuch as ethyl carbamate, various keto-enols such as acetyl acetone;various ketoximes such as methyl ethyl ketoximes or various block agents(blocking agents) such as sodium hydrogen sulfide (sodium bisulfate), orthe like;

using these, various isocyanate compounds such as hexamethylenediisocyanate, isophorone diisocyanate, tolylene diisocyanate, xylylenediisocyanate or diphenyl methane diisocyanate, or the like, orprepolymers thereof, are reacted at a temperature within a range ofapproximately 30° C.-100° C. in the absence of a catalyst, or in thepresence of a catalyst such as dibutyl tin dilaurylate, and theisocyanate groups are thus blocked; a compound having such a form may beemployed.

Furthermore, particularly representative examples of dryer agents whichmay be employed include, for example, various aliphatic carboxylic acidssuch as oleic acid and the like; and various metallic soaps, such assoaps using cobalt salt, manganese salt, zirconium salt, calcium salt,iron salt, or lead salt or the other salt of various aliphaticcarboxylic acids such as oleic acid and the like, and of variousalicyclic carboxylic acids such as naphthenic acid or the like which isused as a carrier, or dryer agents in which an anionic emulsifier, acationic emulsifier, or a non-ionic emulsifier is added to one of themetallic soaps described above in order to make aqueous; it is of coursethe case that these may be used singly or in combinations of two or morethereof.

With respect to the amount of metallic soap and substance which makesthis aqueous which are added, with respect to the metallic component, arange of 0.003 to 0.5 weight percent is appropriate; when the amountadded is less than 0.003 weight percent, it is difficult to produce thedesired effect, while when the metallic component thereof exceeds 0.5weight percent, there is a problem in that especially the waterresistance is worsened, so that neither of these cases is preferable,and the preferable amount of use is appropriately from 0.05 to 0.4weight percent as the metallic component.

Additional examples of the curing agent include various tertiary aminessuch as dimethyl aniline, diethyl aniline, or dimethyl paratoluidine orthe like.

With respect to the amount used of the curing agent, excluding the caseof the dryer agent described above, a proportion within a range ofapproximately 1 part per weight to 50 parts per weight with respect to100 parts per weight of the aqueous vinyl modified epoxy ester resin,calculated on the basis of solid component of the aqueous vinyl modifiedepoxy ester resin, is appropriate, and an amount within this rangepreferably be employed.

Particularly representative examples of the powder or colloid (sol) ofthe metallic oxide include powders or colloids (sols) of SiO₂, Cr₂ O₃,Fe₂ O₃, Fe₃ O₄, MgO, ZrO₂, SnO₂, Al₂ O₃, and Sb₂ O₅, having a particlediameter within a range of 1 to 15 nanometers (nm), and it is possibleto use one or two or more thereof.

With respect to the amount used of the powder or colloid (sol) of themetallic oxide, an amount within a range of approximately 10 parts perweight to 100 parts per weight with respect to 100 per weight of theresin, in solid component of the aqueous vinyl modified epoxy esterresin, is appropriate, and an amount within this range preferable beemployed.

By means of adding the metallic oxide in a colloid form, an organiccomposite-plated steel plate in which the corrosion resistance ismarkedly increased without a reduction in the shininess thereof afterelectro-deposition coating, or a reduction in the adhesion of thecoating material, can be obtained.

In the present invention, a resin composition for coating material for achromate-coated alloy-plated steel plate which is preferably employedcomprises:

100 parts per weight of the solid component (hereinbelow identical) ofan aqueous vinyl modified epoxy ester resin (A-1) which is obtained bymodifying an epoxy ester resin, which is obtained by reacting anaromatic epoxy ester resin and a fatty acid, by means of an additionreaction with a vinyl monomer having as an essential component thereofan ethylenic vinyl monomer containing a carboxylic group, andneutralizing the modified epoxy ester resin using a basic compound;

approximately 10 parts per weight to 100 parts per weight of at leastone powder or colloid (sol) (B) of SiO₂, Cr₂ O₃, Fe₂ O₃, Fe₃ O₄, MgO,ZrO₂, SnO₂, Al₂ O₃, or Sb₂ O₅,

approximately 1 part per weight to 50 parts per weight of a curing agent(C); and

where necessary, 0 to approximately 50 parts per weight of a pigment(D).

Furthermore, in the present invention, in the case in which an aqueousresin composition is used which is obtained by, in place of the aqueousvinyl modified epoxy ester resin and curing agent described above,mixing a vinyl modified epoxy ester resin and a blocked isocyanatecompound described hereinbelow homogeneously at the molecular level, andcausing this to become aqueous, an organic composite plated steel platecan be obtained which has particularly superior rust resistance.

The aqueous resin composition containing an aqueous vinyl modified epoxyester resin in which a blocked isocyanate compound is mixedhomogeneously at the molecular level, which provides superior rustresistance, can be obtained by means of the following preparation.

That is to say, first, while heating and agitating an aromatic epoxyresin and a fatty acid, these are subjected to an esterificationreaction for a period within a range of 2 to 10 hours at a temperaturewithin a range of approximately 150 to 250° C., the obtained material isthen dissolved in an appropriate organic solvent, and a vinyl monomerhaving as an essential component thereof an ethylenic vinyl monomercontaining a carboxylic group and a polymerization initiator are added,then this is heated and agitated at a temperature within a range ofapproximately 50° C. to 150° C. in order to conduct a grafting reaction,and a vinyl modified epoxy ester resin is obtained as the reactionproduct thereof.

Next, the carboxylic groups in the obtained vinyl modified epoxy esterresin are neutralized using a basic compound, and a blocked isocyanatecompound is mixed thereinto conplately.

After this, by means of dispersing this in water, an objective aqueousresin composition containing an aqueous vinyl modified epoxy ester resinin which the blocked isocyanate compound is mixed homogeneously at themolecular level, is obtained.

The operation of mixing uniformly on the molecular level which isreferred to here indicates, concretely, an operation comprising a seriesof processes including a mixing of the neutralized product with ablocked isocyanate compound either in the presence of an organic solventor in the absence of the solvent, and then dispersing the mixture inwater.

That is to say, it is necessary to mix the blocked isocyanate compound,in advance of making the reaction products aqueous, after a part or allof the carboxylic groups present in the reaction product are neutralizedusing a basic substance.

By means of conducting these processes, it is possible to conduct auniform mixing at the molecular level, and it is possible to obtain anaqueous resin composition in a form in which the vinyl modified epoxyester resin and the blocked isocyanate compound are both present in thesame dispersed particles.

With respect to the method by means of which the neutralized product ofthe reaction product is dispersed in water, as described above, it ispossible to add water while agitating the neutralized product, and toconduct phase inversion emulsification, or to add the reaction productinto sufficiently agitated water.

Additionally, a method in which dispersion in water is conducted whileapplying mechanical shearing force, or in which ultrasonic is applied,may also be adopted.

In this manner, it is possible to prepare an aqueous resin compositioncontaining an aqueous vinyl modified epoxy ester resin in which ablocked isocyanate compound which is an essential component of theaqueous resin composition is mixed homogeneously at the molecular level,which has particularly superior rust resistance, and which is employedin the present invention.

With respect to the aqueous resin composition which is used in thepresent invention and which is particularly superior in rust resistance,it is also possible to concomitantly use a composition containing, inaddition to the aqueous vinyl modified epoxy ester resin into which ablocked isocyanate compound is homogeneously mixed at the molecularlevel, if necessary, a curing agent for curing this aqueous vinylmodified epoxy ester resin, and/or a powder or a colloid (sol) of aspecified metallic oxide for the purpose of increasing the corrosionresistance.

The resin composition for coating material for chromate-coatedalloy-plated steel plates which have superior rust resistance which ispreferably used in the present invention comprises, respectively:

100 parts per weight of an aqueous vinyl modified epoxy ester resincontaining a blocked isocyanate compound (A-2) which is obtained bymodifying an epoxy ester resin, obtained by reacting an aromatic epoxyester resin with a fatty acid, by means of the addition reaction of avinyl monomer having a an essential component thereof an ethylenic vinylmonomer containing a carboxylic group, and mixing the resulting vinylmodified epoxy ester resin with a blocked isocyanate compoundhomogeneously on the molecular level so as to make aqueous;

approximately 10 parts per weight to 100 parts per weight of at leastone powder or colloid (sol) (b) of SiO₂, Cr₂ O₃, Fe₂ O₃, Fe₃ O₄, MgO,SnO₂, Al₂ O₃, or Sb₂ O₅ ;

if necessary, 0 to 50 parts per weight of a curing agent (C); and

if necessary, 0 to 50 parts per weight of a pigment (D).

In this manner, an aqueous resin composition which is used in thepresent invention can be obtained. In the organic composite-plated steelplate in accordance with the present invention, the amount of organiccoating film comprising this aqueous resin composition should preferablybe within a range of approximately 0.2 g/m² to 3.0 g/m². If the amountof organic coating film is less than 0.2 g/m², then it becomes difficultto guarantee the post-working bare corrosion resistance, while on theother hand, when the amount thereof exceeds 3.0 g/m², the electrodeposition coating property and the like becomes inferior, and as aresult, it becomes impossible to guarantee an electro-deposited coatingfilm possessing superior shininess and the like.

In the aqueous resin composition, it is possible to blend into theaqueous resin composition, in addition to pigments or aqueous pigmentcompositions, and all the components described above, variouscommonly-known additives such as, if necessary, plasticizer, emulsion orstyrene-butadiene-type latex, other aqueous resins, or silane couplingagents which provide improved adhesion, which are commonly used incoating materials.

In executing the present invention, the aqueous resin composition may beapplied by means of various methods such as dipping coating, showercoating, electro-deposition coating, brush coating, spray coating, orroll coating or the like, and cured after coating.

It is preferably that the target organic composite-plated steel plate beobtained by curing at a temperature of approximately 100° C. or more andfor a freely selected period of time.

The organic composite-plated steel plate in accordance with the presentinvention exhibits extremely superior effects in an organiccomposite-plated steel plate applied to use as a steel plate forautomobiles and the like which is produced by means of executing asucceeding electro-deposition coating.

The organic composite-plated steel plate obtained by the presentinvention has superior adhesion with the adhesive, has superiorcontinuous weldabilities, superior corrosion resistance after working,and superior electro-deposition coating properties, and moreover, hassuperior coating material adhesion and corrosion resistance, and thecoated surface after electro-deposition coating has superior shininess(smoothness), and furthermore, when an aqueous resin composition inwhich a blocked isocyanate compound and a vinyl modified epoxy esterresin are mixed homogeneously on the molecular level is used, the rustresistance is particularly superior.

Next, an explanation will be given of the evaluation methods of the maincharacteristics of the organic composite-plated steel plate obtained bythe present invention; furthermore, the evaluation standards for thevarious characteristics are as given below.

That is to say, first, in the evaluation method for shininess andcoating material adhesion, electro-deposition coating was conducted soas to produce a 20 micron (μm) coating film using commercially-availableelectro-deposition coating materials, and this was baked at atemperature of 175° C., and then the shininess thereof was evaluated.

The shininess was measured using a PGD for electro-deposited coatingfilm. Evaluation standards are shown in Table 1.

With respect to the coating material adhesion, after electro-depositioncoating, an intermediate coat and a finish coat of 40 microns (μm) eachwere executed using a melamine-alkyd resin-type coating material, andthis was drawn in accordance with JIS K-5400, and an Erichsen cross-cutadhesion test was conducted.

Furthermore, after coating, a sample which had been immersed for aperiod of 240 hours in water at a temperature of 50° C. was similarlysubjected to evaluation. That is to say, this evaluated coating materialadhesion after the hot water test. The evaluation standards for thiscoating material adhesion are as shown in Table 2.

                  TABLE 1                                                         ______________________________________                                        Evaluation Index                                                                             PGD                                                            ______________________________________                                        ⊚                                                                             0.6 or more                                                      ∘        less than 0.6˜0.5                                  Δ         less than 0.5˜0.4                                       X            less than 0.4˜0.3                                          XX           less than 0.3˜0.0                                        ______________________________________                                    

                  TABLE 2                                                         ______________________________________                                        Evaluation Index                                                                           Surface Area of Peeled Film                                      ______________________________________                                        ⊚                                                                           0%                                                                 ∘           0˜1%                                            Δ             1˜10%                                               X               10˜50%                                                  XX              50% or more                                                 ______________________________________                                    

Furthermore, the post-working bare corrosion resistance was evaluated byfirst press-working a sample plate, and then evaluating the corrosionresistance of the press-worked part; this corrosion resistance wasevaluated by means of a salt spray testing method conducted inaccordance with the stipulations of JIS Z-2371, in which the conditionswere such that the sodium chloride concentration was 5 weight percent,the temperature within the vessel was 35° C., and the spray pressure was20 PSI.

The presence or absence of rust after a period of 5,000 hours exposureand the degree of rust generation were investigated, and an evaluationwas conducted based on the surface area in which rust occurred; theevaluation standards are shown in Table 3.

                  TABLE 3                                                         ______________________________________                                        Evaluation Index                                                                            Rust Formation Ratio                                            ______________________________________                                        ⊚                                                                            0%                                                                ∘           0˜1%                                            Δ             1˜10%                                               X               10˜50%                                                  XX              50% or more                                                 ______________________________________                                    

Herein, first, the adhesion with the adhesives consists of the tensileshearing adhesive strength and the peeling adhesive strength, and thesewere evaluated in accordance with the stipulations of JIS K-6850 and JISK-6854 on the basis of the evaluation standards shown in Tables 4 and 5.

                  TABLE 4                                                         ______________________________________                                        Evalution Index                                                                           Tensile Shearing Adhesive Strength                                ______________________________________                                        ⊚                                                                          more than 150 kg/cm.sup.2                                           ∘       100˜150 kg/cm.sup.2                                 Δ         50˜100 kg/cm.sup.2                                      X           30˜50 kg/cm.sup.2                                           XX          less than 30 kg/cm.sup.2                                        ______________________________________                                    

                  TABLE 5                                                         ______________________________________                                        Evaluation Index                                                                            Peeling Adhesive Strength                                       ______________________________________                                        ⊚                                                                            more than 15 kg/cm.sup.2                                          ∘        10˜15 kg/cm.sup.2                                  Δ          5˜10 kg/cm.sup.2                                       X            3˜5 kg/cm.sup.2                                            XX           less than 3 kg/cm.sup.2                                        ______________________________________                                    

Next, with respect to continuous weldabilities, welding was conductedusing CF-type electrodes comprising a Cu-Cr material, wherein theconditions were such that the welding force was 250 kgf, and the weldingtime was 0.2 seconds. With respect to the welding current, the currentat which dust generates, and the current at which fusing occurs, weremeasured, currents within the range between the above two current valuewere defined as appropriate welding current, and the intermediate valueof this appropriate welding current range [(current at which dustgenerates+current at which fising occurs)+1/2] was established as thewelding current, and continuous welding was conducted within thiswelding current.

Furthermore, at every 100 points, the nugget diameter was measured, andthe number of points passed until the nugget diameter reached 5 mm wasevaluated based on the evaluation standards shown in Table 6.

                  TABLE 6                                                         ______________________________________                                        Evaluation Index                                                                            Continuous Points                                               ______________________________________                                        ⊚                                                                            more than 5,000 points                                            ∘      3,000 points˜5,000 points                            Δ       1,000 points˜3,000 points                                 X        500 points˜1,000 points                                        XX         300 points or fewer                                              ______________________________________                                    

Furthermore, with respect to rust resistance, a 1-cycle operationconsisted of immersing a sample in a 5 weight percent aqueous solutionof sodium chloride which was saturated with iron rust for a period of 15minutes, and this was then dried for 15 minutes; the state of rustoccurrence was visually evaluated at a point in time after thisoperation had been repeatedly conducted for 200 cycles, and theevaluation was conducted based on the evaluation standard shown in Table7.

                  TABLE 7                                                         ______________________________________                                        Evaluation Index                                                                            Rust Formation Ratio                                            ______________________________________                                        ⊚                                                                            more than 5,000 points                                            ∘      3,000 points˜5,000 points                            Δ       1,000 points˜3,000 points                                 X            500 points˜1,000 points                                    XX         300 points or fewer                                              ______________________________________                                    

EXAMPLES

Next, the present invention will be explained in detail based onreference examples, Examples, and Comparative Examples; however, thepresent invention is not limited to these examples insofar as thetechnological concept thereof is not deviated therefrom. Unlessotherwise limited, the parts and percentages all refer to a weightstandard.

Reference Example 1 Preparation Example of Aqueous Vinyl Modified EpoxyEster Resin (A-1)

60 parts of a dehydrogenated caster oil fatty acid, 60 parts of asoybean oil fatty acid, 30 parts of a safflower oil fatty acid, 225parts of "EPICLON 1050" (trade name; produced by Dainippon Ink andChemicals Inc.), and 0.2 parts of dimethyl benzyl amine were charged ina clean reaction vessel equipped a temperature regulator and an agitatorunder nitrogen gas flow, the temperature thereof was raised to 180° C.,reaction was conducted for one hour, the temperature was then furtherraised to 230° C., and reaction was continued until an acid valuereached to 10.

Next, after this was cooled to 100° C., 250 parts of butyl cellosolvewere charged, then the temperature thereof was raised to 120° C. whilesufficiently agitating, and thereinto, taking over a period of 4 hours,were charged 50 parts of methacrylic acid, 33 parts of acrylic acid, 25parts of 2-hydroxyethyl acrylate, 25 parts of 2-hydroxyethylmethacrylate, and 25 parts of tert-butyl peroxide, and this was thenallowed to maintain for 4 hours.

After this was then cooled to a temperature of 50° C., 110 parts oftriethyl amine were added while well agitating, and 440 parts ofde-ionized water were charged thereinto, and a milk-white objectiveresin liquid having a 40% non-volatile component was obtained.Hereinbelow, this is referred to as "resin (A-1-1)".

In this resin (A-1-1), the proportion of aromatic epoxy resin and fattyacid is 60:40 (weight ratio, hereinbelow identical), and with respect tothe amounts of whole ethylenic vinyl monomer and ethylenic vinyl monomercontaining carboxylic groups, these were, respectively, 35.5 parts and22.1 parts with respect to 100 parts of the reaction product of thearomatic epoxy resin and the fatty acid.

Reference Example 2 As above

75 parts of dehydrogenated castor oil fatty acid, 75 parts of soybeanoil fatty acid, 75 parts of safflower oil fatty acid, 150 parts of"EPICLON 1050", and 0.2 parts of dimethyl benzyl amine were placed in aclean reaction vessel which was equipped a temperature regulator and anagitator under a nitrogen gas flow, the temperature thereof was raisedto 180° C., and a reaction was carried out for a period of 1 hour, thetemperature was then further raised to 230° C., and the reaction wascontinued until an acid value reached to 5.

After this was then cooled to a temperature of 100° C., 250 parts ofbutyl cellosolve were added, the temperature was raised to 120° C. whilesufficiently agitating, and thereinto were charged, taking over a periodof 4 hours, 40 parts of acrylic acid, 25 parts of 2-hydroxyethylacrylate, 25 parts of styrene, and 20 parts of tert-butyl peroxide, andthis was allowed to maintain for a period of 4 hours.

After cooling to 50° C., 60 parts of triethyl amine were added, and417.5 parts of de-ionized water were charged thereinto whilesufficiently agitating, and the objective resin liquid, which wasmilk-white and had 40% non-volatile components, was obtained.Hereinbelow, this is termed"resin (A-1-2)".

In this resin (A-1-2), the proportion of aromatic epoxy resin and fattyacid was 40:60, and the amounts of whole ethylenic vinyl monomer andethylenic vinyl monomer containing carboxylic groups which were usedwere, respectively, 24 parts and 10.5 parts, with respect to 100 partsof the reaction product of the aromatic epoxy resin and the fatty acid.

Reference Example 3 Preparation Example of Aqueous Vinyl Modified EpoxyEster Resin (A-2)

60 parts of dehydrogenated castor oil fatty acid, 60 parts of soybeanoil fatty acid, 30 parts of safflower oil fatty acid, 225 parts of"EPICLON 1050", and 0.2 parts of dimethyl benzyl amine were placed undera nitrogen gas flow in a clean reaction vessel which was equipped atemperature regulator and an agitator, the temperature was raised to180° C., a reaction was carried out for a period of 1 hour, thetemperature was further raised to 230° C., and reaction was carried outuntil an acid value reached to 10.

Next, after this was cooled to a temperature of 100° C., 250 parts ofbutyl cellosolve were added, then the temperature thereof was raised to120° C. while sufficiently agitating, and thereinto was charged, takingover a period of 4 hours, 50 parts of acrylic acid, 25 parts of2-hydroxyethyl acrylate, and 10 parts of tert-butyl peroxide, and thiswas then allowed to maintain for a period of 4 hours.

Then the temperature was cooled to 50° C., and 77 parts of triethylamine were added, and this was sufficiently agitated. Next, 30 parts ofa hexamethylene diisocyanate--methylethyl ketoxime--blocked substancewas added as a blocked isocyanate compound, and this was sufficientlymixed for a period of 30 minutes.

After this, 408 parts of de-ionized water were charged thereinto, whileconducting agitation, and the objective resin liquid, which wasmilk-white in color and which had 40% non-volatile components, and inwhich a blocked isocyanate compound and vinyl modified epoxy ester resinwere mixed on the molecular level, was obtained. Hereinbelow, this istermed "resin (A-2-1)".

In this resin (A-2-1), the proportion of aromatic epoxy resin and fattyacid was 60:40, and the amounts of whole ethylenic vinyl monomer andethylenic vinyl monomer containing carboxylic groups were, respectively,20 parts and 13.3 parts, with respect to 100 parts of the reactionproduct of the aromatic epoxy resin and the fatty acid. Furthermore, theproportion of blocked isocyanate compound contained was 6% of the solidcomponent of resin (A-2-1).

Examples 1-9 and Comparative Examples 1-5

The resin liquids obtained in Reference Examples 1-3 were blended in theproportions shown in Table 8 (shown in solid component proportions), andvarious resin compositions for coating materials for chromate-coatedalloy-plated steel plates were prepared.

In Table 8, in the "Type of Resin" column, reference A indicates theresin (A-1-1) obtained in Reference Example 1, reference B indicates theresin (A-1-2) obtained in Reference Example 2, and reference C indicatesthe resin (A-2-1) obtained in Reference Example 3.

A commercially-available carboxylated polyethylenic emulsion (X) and anaromatic epoxy emulsion (Y) were employed as comparative example.Furthermore, as the curing agents, a hexamethylenediisocyanate--methylethyl ketoxime--blocked substance which was madeaqueous using a non-ionic dispersant (α), a diphenyl methanediisocyanate--methylethyl ketoxime--blocked substance which was madeaqueous using a non-ionic dispersant (β), and "CYMEL 303" (trade name:produced by Mitsui Scitech) (γ) were employed.

Furthermore, with respect to the powders or colloids (sols) of metallicoxides, an aqueous dispersion (M1) of SiO₂ having an average particlediameter of 10 nm, an aqueous dispersion (M2) of Cr₂ O₃ having anaverage particle diameter of 8 nm, and Al₂ O₃ (M3) having an averageparticle diameter of 6 nm, were employed.

Furthermore, with respect to the pigment, an aqueous pigment (producedby Dainippon Ink and Chemicals, Inc.) was employed in which an azoleicpigment was dispersed by using a non-ionic dispersant.

                  TABLE 8                                                         ______________________________________                                                           Example 1 Example 2                                                                             Example 3                                ______________________________________                                          Type of Resin A          100    100     100                                   Type of     α         10                                                Curing Agent β                   20                                                  γ                            5                              Metallic Colloid  M1        20                                                               M2                   50                                                       M3                               30                          Aqueous Pigment                     5                                           Type of Plating          Zn--Ni   Zn--Ni    Zn--Ni                            Amount of Majour Metal       87.2     87.2     86.5                           Amount of Minor Metal   Ni = 12.8 Ni = 12.8  Ni = 13.5                        Amount of Plating Film      20      20     20                               ______________________________________                                         [Notes for Table 8                                                            The reference to the "Amount of Major Metal" in the Table indicates "the      amount of Major metal (Zn) contained in the plating"; and the value is        indicated by weight percent.                                                  In the Table, the reference to the "Amount of Minor Metal" indicates the      name of the metal in question, and also displays the percentage of the        metal contained (weight percent).                                             In the Table, the units for the "Amount of Plating Film" are g/m.sup.2.  

                   Example 1 Example 2 Example 3                                  ______________________________________                                          Type of Chromate    Electrolytic   Applied   Reactive                         Amount of Chromate Film      85      48      48                               Amount of Inorganic/     0.5      0.4    0.6                                  Organic Composite Film                                                        Adhesion with Adhesive       ⊚      ⊚                                             ⊚                            Continuous Weldabilities      ⊚      ⊚                                             ⊚                           Post-working Bare    ⊚      ⊚                                                    ⊚                             Corrosion Resistance                                                          Electro-deposition      ⊚      ⊚                                                 ⊚                             Coating Properties                                                            Coating Material     ⊚      ⊚                                                    ⊚                             Adhesion Properties (1)                                                       Coating Material     ⊚      ⊚                                                    ⊚                             Adhesion Properties (2)                                                       Corrosion Resistance       ⊚      ⊚                                              ⊚                             Shininess       ⊚      ⊚      .circleincir                                       cle.                                         Rust Resistance      ∘      ∘      ∘    ______________________________________                                         [Notes for Table 8                                                            The units of the "Amount of Chromate Coating film" in the Table are           mg/m.sup.2.                                                                   The units of the "Amount of Inorganic/Organic Composite Film" in the Tabl     are g/m.sup.2.                                                                In the Table, the reference to the "Coating Material Adhesion Properties      (1)" indicates the coating materiai adhesion in the normal state, while       "Coating Material Adhesion Properties (2)" indicates the coating material     adhesion after the hot water test.                                       

                       Example 4 Example 5                                                                             Example 6                                ______________________________________                                          Type of Resin  A    100                                                                B            100                                                              C                  100                                               Type of Curing Agent    α   15      10                                  Metallic Colloid    M1    40              20                                            M2           20                                                   Aqueous Pigment                                                                               5                                                               Type of Plating        Zn--Ni   Zn--Mn    Zn--Ni--                            Amount of Majour Metal       85.9  58    86.9                                 Amount of Minor Metal    Ni = 14.1 Mn = 42  Ni = 12.1                                              Co = 1.0                                                 Amount of Plating Film     20       25      20                              ______________________________________                                         [Notes for Table 8                                                            In the Table, the "Zn--Ni--" shown for Example 5 is a shortened form of       "Zn--Hi--Co".                                                            

                   Example 4 Example 5 Example 6                                  ______________________________________                                          Type of Chromate   Applied   Electrolytic  Electrolytic                       Amount of Chromate Film    43       41      85                                Amount of Inorganic/      0.6    0.8     1.3                                  Organic Composite Film                                                        Adhesion with Adhesive      ⊚      ⊚                                             ⊚                             Continuous Weldabilities      ⊚      ⊚                                             ⊚                           Post-Working Bare       ⊚      ⊚                                                 ⊚                             Corrosion Resistance                                                          Electro-deposition       ⊚       ⊚                                               ⊚                             Coating Properties                                                            Coating Material     ⊚     ⊚     .circlein                                       circle.                                      Adhesion Properties (1)                                                       Coating Material     ⊚    ⊚   .circleincir                                       cle.                                         Adhesion Properties (2)                                                       Corrosion Resistance  ⊚     ⊚                                                    ⊚                             Shininess               ⊚      ⊚                                                 ⊚                             Rust Resistance     ∘      ∘      .circleincircl                                       e.                                         ______________________________________                                                           Example 7 Example 8                                                                             Example 9                                ______________________________________                                          Type of Resin     C    100     100     100                                    Type of Curing Agent    β         5                                      Metallic Colloid   M1    50                                                           M2          50       20                                             Aqueous Pigment                    10                                           Type of Plating        Zn--Cr   Zn--Fe   Zn--Al                               Amount of Major Metal     88.5     89       95                                Amount of Minor Metal    Cr = 11.5  Fe = 11.0  Al = 5                         Amount of Plating Film      20       23       45                            ______________________________________                                                       Example 7 Example 8 Example 9                                  ______________________________________                                          Type of Chromate    Applied   Applied    Electrolytic                         Amount of Chromate Film      52       38       75                             Amount of Inorganic/     1.1     1.5     1.5                                  Organic Composite Film                                                        Adhesion with Adhesive      ⊚     ⊚                                              ⊚                             Continuous Weldabilities       ⊚     ⊚                                            ⊚                            Post-Working Bare      ⊚     ⊚                                                   ⊚                             Corrosion Resistance                                                          Electro-deposition      ⊚     ⊚                                                  ⊚                             Coating Properties                                                            Coating Material      ⊚     ⊚                                                    ⊚                             Adhesion Properties (1)                                                       Coating Material      ⊚     ⊚                                                    ⊚                             Adhesion Properties (2)                                                       Corrosion Resistance        ⊚     ⊚                                              ⊚                             Shininess        ⊚     ⊚     .circleincirc                                       le.                                          Rust Resistance       ⊚     ⊚                                                    ⊚                           ______________________________________                                    

Next, the various chromate coating films shown in FIG. 9 were formed onplated steel plates having the deposited amounts and plate compositionsshown in Table 9, and the resin compositions for coating materials forchromate-coated alloy-plated steel plates shown above were applied, andthese were dried and cured for a period of 10 seconds at a temperatureof 150° C. The results of the evaluations of the organiccomposite-plated steel plates obtained in this manner are also compiledand shown in the same Table.

                  TABLE 9                                                         ______________________________________                                                           Comparative                                                                             Comparative                                                                           Comparative                              ______________________________________                                              Example 1    Example 2     Example 3                                      Resin Type   X   100       100                                                         Y                  100                                               Type of      α   30              10                                     Curing Agent    β          20                                            Metallic Colloid    M1   50              30                                            M2            30                                                   Type of Plating                                                                              Zn--Ni    Zn--Ni    Zn--Ni                                       Amount of Major Metal     87.4    89.2    85.8                                Amount of Minor Metal      Ni = 12.6 Ni = 10.8 Ni = 14.2                      Amount of Plating Film      20       20       20                            ______________________________________                                                 Comparative   Comparative  Comparative                                        Example 1    Example 2    Example 3                                  ______________________________________                                          Type of Chromate   Electrolytic    Applied   Applied                          Amount of Chromate      75       48       56                                  Film                                                                          Amount of Inorganic/     0.8     1.2     1.7                                  Organic Composite Film                                                        Adhesion with Adhesive       X      X       ⊚                  Continuous Welding      ⊚     ⊚      X                                            Properties                                  Post-working Bare     ⊚     ⊚      X                                              Corrosion Resistance                        Electro-deposition       X      X       X                                     Coating Properties                                                            Coating Materia1       X      X       ⊚                        Adhesion Properties (1)                                                       Coating Material      X      X       ⊚                         Adhesion Properties (2)                                                       Corrosion Resistance        ∘     ∘                                                    ⊚                             Shininess        X      X       X                                             Rust Resistance       X      X       X                                      ______________________________________                                                            Comparative                                                                             Comparative                                               Example 4    Example 5                                              ______________________________________                                          Resin Type       Y    100      100                                            Type of      β   10                                                      Curing Agent     γ           15                                         Metallic Colloid     M2   30                                                      M3           20                                                         Type of Plating Zn--Ni    Zn--Ni                                                Amount of Majour Metal     86.9     88.2                                      Amount of Minor Metal      Ni = 13.1 Ni = 11.8                                Amount of Plating Film      20      20                                      ______________________________________                                                 Comparative Comparative                                                       Example 4   Example 5                                                ______________________________________                                          Type of Chromate     Electrolytic   Applied                                   Amount of Chromate       82       42                                          Film                                                                          Amount of Inorganic/      0.7     1.3                                         Organic Composite Film                                                        Adhesion with Adhesive        ⊚     ⊚                                    Continuous Weiding      X       X                    Properties                                                                    Post-working Bare      X       X                                              Corrosion Resistance                                                          Electro-deposition      X       X                                             Coating Properties                                                            Coating Material      ⊚      ⊚                  Adhesion Properties (1)                                                       Coating Material      ⊚      ⊚                  Adhesion Properties (2)                                                       Corrosion Resistance          ⊚      ⊚                                   Shininess          X       X                         Rust Resistance        X       X                                            ______________________________________                                    

Industrial Applicability

The organic composite-plated steel plate obtained in accordance with thepresent invention described above has superior adhesion with adhesives,superior continuous welding properties, superior post-working corrosionresistance, and superior electro-deposition coating properties, andmoreover, has superior coating material adhesion, and corrosionresistance, and the coated surface thereof, after electro-depositioncoating, has particularly superior shininess (smoothness), andfurthermore, when an aqueous resin composition is employed in which ablocked isocyanate compound and a vinyl modified epoxy ester resin arehomogeneously mixed on the molecular level, the resulting steel platehas superior rust resistance, so that in particular, by carrying outsuccessive electro-deposition coating, the steel plate which is obtainedexhibits extremely superior effects as an organic composite plated steelplate which is adapted for use as a steel plate for use in automobilesand the like.

We claim:
 1. A resin composition for coating materials forchromate-coated alloy-plated steel plates comprising:an aqueous vinylmodified epoxy ester resin (A-1) obtained by modifying an epoxy esterresin, obtained by the reaction of an aromatic epoxy resin and a fattyacid, by means of the addition reaction of a vinyl monomer having as anessential component thereof an ethylenic vinyl monomer containingcarboxylic groups, and by neutralizing said modified epoxy ester resinusing a basic compound; at least one selected from the group consistingof powder and a colloid (sol) (B) comprising at least one of SiO₂, Cr₂O₃, Fe₂ O₃, Fe₃ O₄, MgO, ZrO₂, SnO₂, Al₂ O₃, and Sb₂ O₅ ; a curing agent(C); and if necessary, a pigment (D).
 2. A resin composition for coatingmaterials for chromate-coated alloy-plated steel plates comprising:anaqueous vinyl modified epoxy ester resin containing a blocked isocyanatecompound (A-2) obtained by homogeneously mixing, on the molecular level,a vinyl modified epoxy ester resin in which an epoxy ester resin,obtained by the reaction of an aromatic epoxy resin and a fatty acid, ismodified by means of an addition reaction of a vinyl monomer having asan essential component thereof an ethylenic vinyl monomer containingcarboxylic groups, with a blocked isocyanate compound, so as to beaqueous; at least one selected from the group consisting of a powder anda colloid (sol) (B) comprising at least one of SiO₂, Cr₂ O₃, Fe₂ O₃, Fe₃O₄, ZrO₂, SnO₂, Al₂ O₃, and Sb₂ O₅ ; a curing agent (C); and ifnecessary, a pigment (D).
 3. A resin composition according to claim 1,wherein the number average molecular weight of said aromatic epoxy resinis within a range of 800 to 6,000.
 4. A resin composition according toclaim 2, wherein the number average molecular weight of said aromaticepoxy resin is within a range of 800 to 6,000.
 5. A resin compositionaccording to claim 2, wherein said homogeneously mixing on the molecularlevel comprises a series of processes including a mixing of theneutralized product with a blocked isocyanate compound either in thepresence of an organic solvent or in the absence of the solvent and thendispersing the resulting mixture in the water.
 6. A resin compositionaccording to claim 1, wherein said resin composition comprises:100 partsby weight of the solid component of an aqueous vinyl modified epoxyester resin (A-1); 10 parts by weight to 100 parts by weight of at leastone powder or colloid (sol) (B); 1 part by weight of 50 parts by weightof a curing agent (C); and where necessary , 0 to 50 parts by weight ofa pigment.
 7. A resin composition according to claim 2, wherein saidresin composition comprises:100 parts by weight of the solid componentof an aqueous vinyl modified epoxy ester resin containing a blockedisocyanate compound (A-2); 10 parts by weight to 100 parts by weight ofat least one powder or colloid (sol) (B); if necessary, 0 to 50 parts byweight of a curing agent (C); and if necessary, 0 to 50 parts by weightof a pigment (D).